Got a PS2 mouse. It has both ports for M and KB. I have a USB mouse anyways.
Should have got a USB one so that I can use it with my PS3. No other problems otherwise.
PS2 are prone to ghosting and have a slightly higher input lag than a USB KB. Found during my research.
This is an old post. Any mod stumbling upon this is free to lock it.
PS/2 or USB?
PS/2 wins on three fronts: First, it supports full n-key rollover(Max no. of key registered at once). Second, PS/2 keyboards aren't polled, but are completely interrupt based. And third, it is impossible for it to be delayed by the USB bus being used by other devices. There are two types of USB transfer modes - the interrupt transfer mode (USB polls keyboard, when key is sensed the USB controller sends the interrupt to the CPU), and the isochronous transfer mode, which reserves a certain amount of bandwidth for the keyboard with a guaranteed latency on the bus. Unfortunately, there are absolutely no keyboards made that use the latter, because special controllers would have to be used, thus making it cost prohibitive.
So if your keyboard supports both PS/2 and USB, and your PC has a PS/2 port, there's no reason not to use it.